70X is just right for both of those cards, but it doesn't tell the whole story. If you use a program like HD Tach, you'll find that those two cards have very different random access times, which is very important to the performance of the card in a flashcart. The Kingston Japan will have much faster random access times than the Sandisk, which is why it performs so well in memory-access intensive games.

this is pure speculation i honestly have no clue but i want to say the quality of the materials say the circuits on a microSD are pure metals while in taiwan their standards for quality are much lower meaning the metals are contaminated meaning less conduction.

another thing i found out was relying on speeds given on packages such as 60x are pointless because the real kicker is the random access speed this is why sandisks have high speeds but fail for some roms.

Also i'd like to speak further on kingston and patriot. The reason why theres so much drama over kingston memory is because Kingston sold so many microSDs that they outsourced some of their production to a taiwan manufacturer and several other japanese manufacturers you can see this from thier huge range of serial numbers and variations in decals. Look for SD-CO1G Japan (us modular, pny, kingston, toshibas, Dane-Elec good batches all have this written on them)

i bought a patriot 2gb microsd from newegg. 35 shipped. it is great. speed tested with hd tach is around 9.7mb to 10.2 mb transfer rate. similar to kingston japan 1 gb microsd card. the speed for kingston is 10.1 mb to 10.4 mb transfer rate. hopeful this help people out. fyi this card is made in taiwan
i tested POR briefly i dont see slowdown on start. played 5 minutes no crach yet.